JP6085181B2 - Porous water-swellable elastic material - Google Patents

Description

  The present invention relates to a porous water-swellable elastic material.

Conventionally, as a water-swellable rubber used as a water-stopping material, (1) a water-swelling material in which a water-absorbing resin such as acrylic acid is mixed with a rubber material having high tensile strength such as chloroprene rubber, styrene-butadiene rubber, and butyl rubber Rubber is widely known.
Moreover, as a water-swellable composition using water-swellable clay, (2) a water-swellable composition obtained by mixing water-swellable clay with unvulcanized butyl and (3) water-swellable clay and gelling group A water-swellable composition (for example, Patent Document 1) kneaded and molded with an adhesive composition using oil or asphalt is widely known.

Among these water-swellable rubbers and water-swellable compositions, the water-swellable rubber (1) is very excellent in shape stability due to the tensile strength of the elastic rubber as the main material. However, when it is used as a water-stopping material that fills gaps in concrete joints or the like, there is a problem that the water-absorbing resin constituting the water-swellable rubber expands due to the high swelling pressure, and cracks are generated in the concrete frame.
When the water-swellable composition (2) is mixed with unvulcanized butyl having a low tensile strength and water-swellable clay, the water-swellable composition itself has a low swelling pressure, and is used as a water-stopping material. However, cracks do not occur in the concrete frame. However, since this water-swellable composition has a low tensile strength, there is a problem that it is easily deformed by an external force or the like. This deformation creates a gap between the water stop material and the water stop object, which may cause water leakage.
Even when the water-swellable composition (3) is used as a water-stopping material, the gelled base oil, asphalt, etc., which are the main materials, have very weak tensile strength, so that the shape of the water-stopping material can be easily set by external force or the like. There is a problem of deformation.
The “strength” in the waterstop material is a force that resists an external force, and the “swelling pressure” is a force that pushes around when swollen.

JP 2003-213260 A

  As described above, the water-swellable rubber and the water-swellable composition containing elastic rubber, unvulcanized butyl, water-absorbing resin, water-swellable clay, gelled base oil, and asphalt are all tensile strength and swelling. The balance of pressure was lacking, and it did not necessarily satisfy the demand as a water stop material. That is, the tensile strength is a characteristic necessary for maintaining the shape stability of the water-stopping material, but this tensile strength can suppress the swelling rate of the water-stopping material, and the water-stopping effect due to water absorption may not be sufficiently obtained. In order to obtain a sufficient swelling rate, a high swelling pressure that can resist the tensile strength is required. However, in this case, swelling due to water absorption of the water-stopping material may cause pressure on the water-stopping target object such as a concrete frame and cause cracks.

  In view of the above points, the present invention has sufficient water swelling performance even when a water-swellable material containing an elastic rubber having a high tensile strength and a water-swellable clay having a low swelling pressure is used as a water-stopping material. Another object of the present invention is to provide a porous water-swellable elastic material that has excellent shape stability and suppresses the occurrence of cracks in water-stopping objects such as concrete frames.

  As a result of intensive studies to achieve the above object, the present inventors have determined that pores (voids) are formed in a porous water-swellable elastic material containing an elastic rubber having a high tensile strength and a water-swellable clay having a low swelling pressure. Presence of a predetermined amount makes it easy for water to penetrate into the porous water-swellable elastic material, and it is possible to impart swelling even when using a water-absorbing substance having a low swelling pressure such as water-swellable clay. I found out. Further, it has been found that by reducing the pores, it is possible to prevent a decrease in the tensile strength, and it is possible to achieve both shape stability and swelling property. The present invention has been completed based on these findings.

The object of the present invention has been achieved by the following means.
<1> A porous water-swellable elastic material containing elastic rubber and water-swellable clay having pores therein, a porosity of 1% or more, and a C-type hardness of 71 or more and less than 80.
<2> The porous water-swellable elastic material according to <1>, wherein the number of pores having an equivalent area circle diameter of 3 μm to 2 cm is inside 60% or more of the total number of pores.
<3> The porous water-swellable elastic material according to <1> or <2>, containing 20 to 80 parts by mass of the elastic rubber and 20 to 80 parts by mass of the water-swellable clay.
<4> The porous water-swellable elastic material according to any one of <1> to <3>, wherein the water-swellable clay is at least one selected from bentonite, smectite, and swellable mica.
<5> The porous water-swellable elastic material according to any one of <1> to <4>, wherein the swelling rate is 150% or more.
In the present specification, “pores” are void portions existing inside the porous water-swellable elastic material, and include both independent pores and continuous pores. “Continuous pores” refers to pores that are continuous from an arbitrary surface to other surfaces in the form of passages, and the pores are bent from one surface to the other surface. An “independent hole” refers to one that is not in contact with the outside and is enclosed.
The “porosity” refers to the ratio of the total area of the pores to the total area of any cut surface obtained by cutting the porous water-expandable elastic material. “C-type hardness” in the porous water-swellable elastic material refers to a C-type hardness tester described in the JIS K 6301 hardness test.

  The porous water-swellable elastic material of the present invention has pores so that water can penetrate into the inside, has sufficient water-swelling performance, and generates cracks in water-stopping objects such as concrete frames. And shape stability is improved.

It is a graph showing the relationship between C type hardness and porosity, and the swelling rate of a porous water-swellable elastic material. It is a schematic diagram of the microscope image (entire visual field surface) of the cut surface of the porous water-swellable elastic material created in the example. It is a graph showing the swelling rate measurement result of each test body created in the Example. (A) is the top view which showed typically an example of the water-swellable water stop material which consists of a porous water-swellable elastic material for performing a swelling test, (b) is the side view. It is sectional drawing which shows the II-II line cross section of the water-swellable water stop material of FIG.

<Porous water-swellable elastic material>
The porous water-swellable elastic material of the present invention contains elastic rubber and water-swellable clay. Further, the porous water-swellable elastic material of the present invention has pores therein, the porosity is 1% or more, and the C-type hardness is 71 or more and lower than 80. Note that the porous water-swellable elastic material is not limited to a specific shape, and may be any shape such as a plate material or a bar material.
Hereinafter, preferred embodiments of the present invention will be described. First, elastic rubber and water-swellable clay will be described.

[Elastic rubber]
The elastic rubber constituting the porous water-swellable elastic material used in the present invention is not particularly limited as long as it is a substance exhibiting rubber-like elasticity described in, for example, Iwanami Rikagaku Dictionary 5th Edition (1998, published by Iwanami Shoten). Is not to be done.
Specific examples of elastic rubber include natural rubber, butyl rubber, chloroprene rubber, styrene / butadiene rubber, butadiene rubber, acrylonitrile / butadiene rubber, acrylic rubber, isobutylene rubber, isoprene rubber, ethylene propylene rubber, polyethylene, chlorinated polyethylene, and sulfonated. Polyethylene, chlorinated polypropylene, sulfonated polypropylene, ethylene / vinyl acetate copolymer, polyvinyl chloride or copolymers thereof, urethane rubber, fluororubber, silicone rubber, styrene / isoprene / styrene block copolymer or hydrogenated product thereof General examples such as styrene / isoprene copolymer or hydrogenated product thereof, styrene / butadiene block copolymer or hydrogenated product thereof, styrene / butadiene / styrene block copolymer or hydrogenated product thereof. That.
In this invention, the said elastic rubber can be used individually by 1 type or in combination of 2 or more types.

The porous water-swellable elastic material of the present invention preferably contains 20 to 80 parts by mass of the elastic rubber, more preferably 30 to 70 parts by mass, and even more preferably 40 to 65 parts by mass. .
If the content of the elastic rubber is too small, the tensile strength of the porous water-swellable elastic material is lowered, and the shape stability of the porous water-swellable elastic material may be insufficient. On the other hand, if the amount is too large, the swelling ratio of the porous water-swellable elastic material may be insufficient.

[Water-swelling clay]
As the water-swellable clay used in the porous water-swellable elastic material of the present invention, at least one kind of clay selected from natural or synthetic water-swellable clay is used. Such clay may be unmodified or modified, and is preferably at least one selected from smectite clays such as bentonite and hectorite, and swellable mica.
Among these, bentonite is an inorganic clay that is naturally produced, so it is safe and stable for a long time without being decomposed by microorganisms in the soil. Therefore, it is a particularly preferable clay.

In the porous water-swellable elastic material of the present invention, one kind of clay selected from the water-swellable clays can be used alone or in combination of two or more kinds.
The porous water-swellable elastic material of the present invention preferably contains 20 to 80 parts by mass of the water-swellable clay, more preferably 30 to 70 parts by mass, and 40 to 65 parts by mass. Further preferred.
If the content of the water-swellable clay is too small, the water-swellable rubber may not be able to obtain a sufficient swelling rate. On the other hand, if the amount is too large, the tensile strength of the elastic rubber becomes insufficient, and the shape stability may decrease.

  Next, the porosity which the porous water-swellable elastic material of the present invention has, the porosity and C-type hardness of the porous water-swellable elastic material of the present invention will be described.

[Vacancy]
A plurality of pores are scattered inside the porous water-swellable elastic material of the present invention. Thereby, it becomes easy for water to penetrate into the porous water-swellable elastic material. Further, the water-swellable clay having a low swelling pressure can be sufficiently swollen inside the porous water-swellable elastic material by utilizing the gap between the pores. Furthermore, the tensile strength of the porous water-swellable elastic material is maintained by making the pores into fine voids. Thus, the porous water-swellable elastic material of the present invention maintains high tensile strength and water-swelling function and exhibits excellent shape stability.

  As described above, a plurality of the pores are scattered and contained inside the porous water-swellable elastic material. The porosity, which is the content ratio of the pores, is measured by the following method. This porosity can be adjusted by, for example, foaming of water in water-swellable clay such as bentonite. Moreover, sodium hydrogen carbonate etc. which are thermally decomposed by heating at the time of molding and generate carbon dioxide gas can be used. Furthermore, after providing pores in the water-swellable rubber before molding by the above method, a method of molding, a method of mixing highly volatile solvent to provide pores, a method of mixing liquefied gas and providing pores, Examples include a method in which a material that dissolves in a solvent is mixed, soaked in the solvent after molding, and the material is eluted to provide holes.

(Measurement method of porosity)
The porosity can be measured by the following method. First, the porous water-swellable elastic material is cut using a cutter knife. Next, the cross section is observed with a microscope (manufactured by Keyence Corporation, DHX-2000. Specifically, the magnification of the microscope is fixed to 150 times, and as shown in the schematic diagram of FIG. The total area B of the hole locations in the field of view occupying the total field area A (3,752,762 μm 2) is measured and calculated from the total area B of the hole locations in the field of view / total field area A × 100. Measurement of the total visual field area A and the area of the holes in the visual field is performed using measurement software built in the microscope DHX-2000. This measurement is performed three times, and the average of the measured numerical values is defined as the porosity. .

  In the porous water-swellable elastic material of the present invention, the area equivalent circle diameter of the pores is 3 μm to 2 cm, preferably 20 μm to 1 cm, more preferably 50 μm to the viewpoint of having sufficient swelling performance. 5 mm. If it is smaller than this range, it may be difficult to exhibit an excellent swelling ratio while maintaining a high tensile strength. When it is larger than this range, the specific surface area decreases, so that it may be difficult to exhibit the swelling ratio and the porous water-swellable composition may become brittle. Therefore, it is preferable that the holes having an equivalent area circle diameter of 3 μm to 2 cm are 60% or more of all the holes. The “area equivalent circle diameter of the vacancies” referred to here is the case where the vacancies are converted into a circle from the area of the observable vacancies on the cut surface to be observed in the above (method for measuring the porosity). The diameter of The number of holes having an area equivalent circle diameter of 3 μm to 2 cm is “60% or more of the total number of holes” is a ratio in the cut surface of the observation target, and is used in the above (Method for measuring porosity). The average ratio of the three cut surfaces.

[Porosity and C-type hardness]
As described above, the pores contribute to the swellability of the porous water-swellable elastic material. In addition, the combination of the porosity, which is the content ratio of the pores, and the C-type hardness indicating the shape stability of the porous water-swellable elastic material affects the swelling rate of the porous water-swellable elastic material. This relationship is shown as a graph in FIG. In FIG. 1, “◯” represents a porous water-swellable elastic material having a swelling ratio of 150% or more, and “X” represents a porous water-swellable elastic material that does not reach 150%.
As shown in FIG. 1, when the C-type hardness is 80 or more, a reduction in the swelling rate showing swelling performance is brought about. On the other hand, even if the C-type hardness is lowered, the swelling is not affected. However, if the C-type hardness is lower than 71, the tensile strength is lowered, and when the load is applied for a long time, it may be easily deformed or broken. Therefore, the porous water-swellable elastic material of the present invention has a C-type hardness of 71 or more and less than 80 from the viewpoint of keeping the swelling ratio in a suitable range and maintaining good tensile strength. More preferably, it is 72 or more and 79 or less, More preferably, it is 73 or more and 78 or less.

  On the other hand, if the porosity is too low even if the C-type hardness is 80 or less, the porous water-swellable elastic material does not exhibit sufficient swelling performance. Therefore, the porous water-swellable elastic material of the present invention has a porosity of 1% or more, more preferably 3% or more, and further preferably 5% or more. The upper limit of the porosity is not particularly limited. However, since the shape stability of the molded water-stopping material may be deteriorated when the porosity is higher than 40%, the porosity is preferably 40% or less, more preferably 35% or less. More preferably, it is 30% or less.

(Method for measuring C-type hardness)
The C-type hardness can be measured using, for example, a C-type hardness meter (manufactured by Furusato Seiki Co., Ltd.). This measurement is performed at five locations on the surface of the porous water-swellable elastic material, and the average value is defined as C-type hardness.

[Swelling rate]
The porous water-swellable elastic material of the present invention preferably has a swelling ratio of 150% to 1,000%, more preferably 200% to 600%. This swelling rate is a numerical value indicating the swelling performance of the porous water-swellable elastic material, and is a volume ratio obtained by a measurement method described later. If the swelling rate is too small, a sufficient water-stopping effect may not be obtained, and if it is too large, the above-described crack problem may occur.
In addition, the porous water-swellable elastic material of the present invention has a swelling ratio within the above range after one month from the start of use as a water-stopping material, and the swelling ratio is within the above range even after one month has elapsed. It is preferable to remain within. In this case, while the porous water-swellable elastic material of the present invention absorbs moisture and has a high water-stopping effect, rapid swelling of the entire material is suppressed, and swelling performance is maintained for a long time. Can do. Such long-term swelling performance is obtained by a combination of the above-described numerical ranges of porosity and C-type hardness.

(Measurement method of swelling rate)
The swelling ratio can be measured by the following method. That is, the mass (W1) in the air (temperature 23 ± 2 ° C., humidity 40 ± 10%) before immersion of the porous water-swellable elastic material is measured, and then the mass (W2) in water at 23 ± 2 ° C. Weigh. Next, after soaking in water, take it out quickly, wipe it with a filter paper, etc. to remove the water, measure the mass (W3) of the porous water-swellable elastic material in the air, and then further in water at 23 ± 2 ° C. The mass (W4) of The swelling rate is based on the volume change rate equation of the method described in “JIS K 6301 immersion test”, and the difference in specific gravity is expressed as {(W3−W4) − (W1−W2)} ÷ (W1−W2) × 100. It can be calculated by conversion.

  In addition to the above essential components, the porous water-swellable elastic material of the present invention includes various additive components conventionally used in water-stopping materials as optional components as long as the purpose of the present invention is not impaired. Can be blended. Examples of such additives include softeners (for example, oils such as mineral oils, synthetic oils and fatty oils), stabilizers, antiaging agents for preventing aging due to Nikko and heat, reinforcing agents, antifreezing agents, and antioxidants. Agents, colorants and the like.

  The porous water-swellable elastic material of the present invention can be manufactured by a method adopted as a method for manufacturing this type of material. In producing a porous water-swellable elastic material, there is no particular limitation on the order and method of adding and mixing the components. The porous water-swellable elastic material of the present invention can be obtained as a uniform mixture by sufficiently mixing water-swellable clay and elastic rubber. The following method is mentioned as an example of the preferable manufacturing method of the porous water-swellable elastic material of the present invention.

When 20-80 parts by weight of butyl rubber is used as the elastic rubber and 20-80 parts by weight of bentonite is used as the water-swellable clay, these are kneaded at 20-100 ° C. for 15-120 minutes using a kneader. Thereafter, a porous water-swellable elastic material having a predetermined shape and size can be obtained by vulcanization molding at 120 to 200 ° C. for 3 to 15 minutes.
The porosity inside the porous water-swellable elastic material can be adjusted by combining any of the methods described above.

  The porous water-swellable elastic material of the present invention can be used in any shape depending on the shape of the portion to be disposed as the water-stopping material and the required function. As an example of its use, a part of the porous water-swellable elastic material may be appropriately cut into a necessary shape and size and installed at a water stop. Alternatively, it may be preliminarily molded by vulcanization using a mold having a shape required as a water-stopping material when producing a porous water-swellable elastic material. For example, as shown in FIGS. 4 and 5, a disk-shaped plate-like body having a diameter of 60 to 500 mm and a thickness of 2 to 15 mm and a conical shape having a diameter of 10 to 40 mm and a height of 5 to 40 mm as shown in FIGS. And a hole having a diameter of 5 to 20 mm and a depth of 5 to 40 mm at the center of the protrusion.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these.

Example 1
Bentonite (Kunimine Kogyo Co., Ltd .; trade name: Kunigel VA) 50 parts by weight, butyl rubber hardness 40 degrees 50 parts by weight, additive (oil trade name: Cosmo Pure Safety 150 Cosmo Oil Lubricants) 6.5 parts by weight And kneaded at 60 ° C. for 40 minutes. After that, vulcanization molding was performed at 160 ° C. for 6 minutes using a mold, a disc-shaped main body having a diameter of about 80 mm and a thickness of 7 mm, a conical projection having a diameter of 40 mm and a height of 10 mm, and a projection A porous water-swellable elastic material having a hole with a diameter of 20 mm and a depth of 10 mm at the center of the part was obtained (see FIGS. 4 and 5).
The water content of the bentonite used was 11.2% by mass. Further, the porosity was 24.80%, and the equivalent circle diameter was 1.89 to 494.9 μm.

(Example 2)
In Example 1, the porous water-swellable elastic material of Example 2 was obtained in the same manner as Example 1 except that the moisture of bentonite was 5.7% by mass and the vulcanization molding time was 5 minutes. The porosity was 10.51%, and the equivalent circle diameter was 18.74-539.58 μm.

(Example 3)
A porous water-swellable elastic material of Example 3 was obtained in the same manner as in Example 1 except that the moisture content of bentonite was 5.7% by mass and the vulcanization molding time was 6 minutes. The porosity was 10.28%, and the equivalent circle diameter was 19.71 to 439.48 μm.

Example 4
In Example 1, the porous water-swellable elastic material of Example 4 was obtained in the same manner as in Example 1 except that the moisture of bentonite was 2.4% by mass and the vulcanization molding conditions were 140 ° C. for 4 minutes. It was. The porosity was 1.43%, and the area equivalent circle diameter was 17.2 to 112.5 μm.

(Example 5)
In Example 1, the porous water-swellable elastic material of Example 5 was used in the same manner as in Example 1 except that the water content of bentonite was 11.2% by mass and the vulcanization molding conditions were set at 140 ° C. for 4 minutes. Obtained. The porosity was 4.30%, and the area equivalent circle diameter was 17.3 to 212.2 μm.

(Comparative Examples 1-3)
In Example 1, the moisture content of bentonite was 2.4% by mass, and the vulcanization molding time was 5 minutes, 5 minutes 30 seconds, and 6 minutes, respectively. The porous water-swellable elastic materials of Examples 1 to 3 were obtained. Porosity: 1.19%, 0.96%, 0.86%, equivalent area circle diameter: 19.0-111.0 μm, 19.0-453.09 μm, 16.3-134.7 μm .

(Comparative Example 4 )
In Example 1, the porous water-swellable elastic material of Comparative Example 5 was prepared in the same manner as in Example 1 except that the water content of bentonite was 11.2% by mass and the vulcanization molding condition was 120 ° C. for 4 minutes. Obtained. The porosity was 18.75%, and the area equivalent circle diameter was 19.1 to 523.0 μm.

About the porous water-swellable elastic materials obtained in Examples 1 to 5 and Comparative Examples 1 to 4 , the above-mentioned (Measurement method of porosity), (Measurement method of C-type hardness), and (Measurement method of swelling ratio) ). The results are shown in Table 1 below. In the column of the swelling rate shown in Table 1, when the swelling ratio is less than 1.5 times after 1 month as a water-swellable water-stopping material, the time for swelling and closing the pores becomes long, and the initial water-stop effect In the case where the swelling ratio is 1.5 times or more after one month, the product having a swelling ratio of 1.5 or more was judged as “good”, and the product having a swelling ratio less than that was designated as “x”. In addition, the shape stability was C type altitude 71 or higher where the shape is stable, and “X” was lower than 71.
Moreover, the time-dependent change of the swelling rate measured about the sample of the Example and the comparative example is shown in FIG. In addition, the swelling rate after one month means that each porous water-swellable elastic material thus prepared was completely immersed in water for one month and stored at 23 ± 2 ° C. Measured based on Moreover, the swelling rate in the elapsed days shown in FIG.

Each sample of each example had a good swelling rate. Further, the samples of each example had a porosity of 1% or more and a C-type hardness of 71 or more and less than 80, and maintained excellent tensile strength as well as good swelling rate and excellent shape stability. On the other hand, Comparative Examples 1 to 3 all had high tensile strength and excellent shape stability, but the swelling rate was poor. In Comparative Example 4 , although the swelling rate was excellent, the tensile strength was low and the shape stability was inferior.

DESCRIPTION OF SYMBOLS 1 Water stop material 3 Plate-shaped main body 4 Protrusion part 5 Hole 6 Whole view surface in the cut surface of porous water-swellable elastic material 7 Portions other than the hole in the cut surface of porous water-swellable elastic material 8 Hole portion

Claims (5)

  A porous water-swellable elastic material containing elastic rubber and water-swellable clay, having pores therein, having a porosity of 1% or more and a C-type hardness of 71 or more and less than 80.   2. The porous water-swellable elastic material according to claim 1, wherein the number of pores having an area equivalent circle diameter of 3 μm to 2 cm is inside 60% or more of the total number of pores.   The porous water-swellable elastic material according to claim 1 or 2, comprising 20 to 80 parts by mass of the elastic rubber and 20 to 80 parts by mass of the water-swellable clay.   The porous water-swellable elastic material according to any one of claims 1 to 3, wherein the water-swellable clay is at least one selected from bentonite, smectite, and swellable mica.   The porous water-swellable elastic material according to any one of claims 1 to 4, having a swelling rate of 150% or more.

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